The present invention relates to optical processors and more particularly to an analog optical processor which requires no light modulator to transduce input electrical signals to optical signals and which uses homodyne detection to maximize dynamic readout of the optical transformed operator.
Complex integral transform operations have been performed by conventional optical processors which require the input signals, one-dimensional or two-dimensional, constituting a spatial matrix of elements. At each of the elements of the spatial matrix, the amplitude and/or phase light may be changed proportionally to an input signal. All elements of the input signal operate simultaneously on the input beam of light. The amplitude transmittance of each element must be modulatable to provide for processing of new signals in a rapid sequence. Heretofore, the application of optical integral transform devices has been inhibited by lack of sufficient means of modulating a light beam with an input signal. Typical light modulators such as ferro-electrics, thermoplastics, photochromics and liquid crystals are subject to degradation or fatigue in use. Furthermore, the dynamic range of the input signal that may be accommodated by such a modulator is limited. A maximum of approximately ten levels is typical, equivalent to a few bits per input element. It is thus desirable to have an apparatus and method for complex filtering of one or two-dimensional signals for complex operations at high speed by an optical-electronic processor which can utilize high density optical read-only or interactive memory.